Mechanical blackboard eraser



Jan. 5, 1965 J. w. BELL MECHANICAL BLACKBOARD ERASER 3 Sheets-Sheet 1 Filed Aug. 17, 1962 INVENTOR. John M. 34?]! Jan. 5, 1965 J. w. BELL MECHANICAL BLACKBOARD ERASER s Sheets-Shet 2 Filed Aug. 1'7, 1962 Jan. 5, 1965 J. w. BELL MECHANICAL BLACKBOARD ERASER Filed Aug. 17, 1962 3 Sheets-Sheet 3 United States Patent O 3,163,943 .MECHANICAL BLACKBOARD ERASER .lohn W. Bell, 24 Pasatiempa Drive, Santa Cruz, Calif. Filed Aug. 17, 1962, Ser. No. 217,694 11 Claims. (CI. 3562) This invention relates to school or other class or lecture room accessories which include a wall-mounted and relatively large blackboard.

The major object of this invention is to provide an erasing device which is adapted to be permanently mounted in connection with the blackboard and manually operative to erase any material chalked thereon.

Another object of the invention is to provide a device for the purpose which is mounted for movement from one end of the blackboard to the other, as the operato may determine to be necessary.

The device includes a vertical wiping and erasing member normally engaging the blackboard as said device is moved therealong, and a further object of the invention is to provide means, controlled by the operator, for withdrawing the wiping and erasing member from contact with the blackboard as the device is being so moved, whereby any chalked matter on said blackboard which is to be left thereon will not be erased with such movement, while enabling the blackboard to be erased on one side or the other of such matter as may be desired.

The wiping and erasing member is in the form of a rotary drum, and another object of the invention is to provide means for cleaning the chalk from the drum as it rotates, and at the same time confining such dust and reventing the same from becoming mingled with the classroom air, as is the case with ordinary hand erasers, and which tend-s to cause throat irritation and consequent coughing.

Also, by the use of my improved erasing device, no chalk dust is deposited on the hands or clothing of the operator, and the blackboard will be kept cleaner than when it is erased by the use of the usual hand erasers. Further, time and effort is saved, and the janitors work is lessened, because the premises remain cleaner.

It is also an object of the invention to provide a mechanical blackboard eraser which is designed for ease and economy of manufacture.

It is also an object of the invention to provide a practical, reliable, and durable mechanical blackboard eraser, and one which will be exceedingly effective for the purpose for which it is designed.

These objects are accomplished by means of such structure and relative arrangement of parts as will fully appear by a perusal of the following specification and claims.

In the drawings:

FIG. 1 is a front elevation of my improved eraser as mounted on a blackboard, and forcshortened.

FIG. 2 is a sectional plan of the device, taken on line 2-2 of FIG. 1.

FIG. 3 is an enlarged transverse sectional elevation, foreshortened, of the device and blackboard, taken on line 3-3 of FIG. 1.

FIG, 4 is a similar view on line 44 of FIG. 1.

FIG. 5 is a sectional plan taken on line 55 of FIG. 3.

Referring now more particularly to the drawings, and to the characters of reference marked thereon, the improved mechanical blackboard eraser which is the subject of this invention is designed for use on a conventional blackboard 1 having top and bottom edge frames or strips 2 and 3 respectively; the latter being formed, as usual, with a forwardly projecting chalk-receiving trough 4.

The erasing device comprises a supporting frame, indicated generally at 5, and which includes horizontal top and bottom C-shaped frame rails 6 which substantially 3,163,943 Patented Jan. 5, 1965 ice overlap the top and bottom edge frames or strips 2 and 3 in front of and close to the same. These rails are connected, centrally between their ends, by a relatively narrow or strip-like vertical C-shaped member 7, which projects back from the frame rails 6 and forms a. rigid unit therewith.

- Slides 8 are mounted on the upper frame 6 adjacent the ends thereof for movement toward and from the adjacent blackboard edge strip 2. Each slide 8 supports a vertical-axis grooved roller 9, the groove of which is engaged at the front by the lip 10 of a longitudinal hanger 11 which extends the full length of said edge strip 2 and is secured thereto.

An adjustable finger screw 12 is mounted on each slide 8 and engages the frame rail 6 in a manner to enable said rail to be adjusted back and forth relative to the edge strip 2 and the blackboard 1, for the purpose which will be seen later. Similarly, slides 13 are mounted on members 14 projecting from the lower frame rail 6; each such slide carrying a vertical-axis roller 15, the groove of which is engaged at the front by a lip 16 formed on a rigid strip 17 secured on, and extending the full length of, the trough 4 along the forward edge thereof. An adjustable finger screw 18 between each slide 13 and member 14 enables the lower frame rail 6 to be adjusted back and forth relative to the lower blackboard edge strip 3.

Extending substantially the full height of the blackboard 1 between and centrally of the length of the frame rail 6, or directly behind the frame member 7, is the chalk wiping and erasing member of drum form, indicated generally at 19. This drum comprises a rigid and preferably hollow core 20 having an axial shaft 21 secured thereto and projecting from both ends thereof. This core 20 is faced with a thick layer of felt or similar yieldable material 22 such as is commonly used for chalk erasing purposes; the felt engaging the blackboard 1.

Axially alined with and projecting from both ends of the shaft 21 are stub shafts 23 connected to said shaft 21 by coupling collars 24. Surrounding each stub shaft 23 between the related collar 24 and the adjacent face of the adjacent frame 6 is a bearing flange 25 in whch said stub shaft is turnable. Said flange 25' slidably engages the adjacent face of the adjacent frame rail 6, and is yieldably urged toward the blackboard 1 by a spring 26 connected between the flange and said frame rail, so that the drum 19 will be held in contact with the blackboard. The opposite or outer end of each stub shaft 23 is fitted with a fixed flange 27 which slidably engages against the outer face of the adjacent frame rail 6. Each stub shaft 23, within the confines of the related frame member, carries a pinion 28 which meshes with a gear 29 journaled in said frame rail. Fixed with each gear is a friction roller 30, which rides against the front face of the adjacent edge frame of the blackboard 1.

An upstanding handle 31 is fixed on and projects outwardly from the frame 7, and by means of which handle the erasing device may be readily moved back and forth along the blackboard 1; said device being supported for such movement with a minimum of friction by the pairs of rollers 9 and 15. With such movement, the drum 19 rotates by reason of the frictional engagement of the friction rollers 30 with the fixed edge strips 2 and 3, and thus erases any matter chalked on the blackboard. The erast ing drum 19 is given a wiping and rubbing action against said blackboard as the drum is rotated, for the reason that the speed of rotation of the drum is increased over that of the friction rollers 30 by the speed increasing gearing 28-29.

When the device is moved in one direction or the other along the blackboard 1, it may be desired at times to leave certain portions of the chalked matter on such blackboard 3. in an untouched or unerased condition. In order to enable this result to be obtained, the following arrangement is provided:

Slidably mounted Within the confines of the handle 31, which is an open C-shaped member, is a vertical trigger bar 32, spaced somewhat from the outer hand-engaged vertical member 33 of the handle; said bar 32 being arranged for horizontal movement toward said handle member 33 from its normal position.

Wire units 34 are connected atone end to the upper and lower extremities of the bar 32, and at the other end to the flanges 25; said units 34 including direction-changing elements 35 mounted on the frame member 7 at the upper and lower ends of handle 31, and at the upper and lower ends of said member 7. These elements 35 are arranged so that the Wire units 34 do not interfere with the drum 19, and straight pulls will be imparted to the flanges 25.

With this arrangement, it will be seen that the springs 26 normally function to pull the erasing drum against the blackboard 1, and maintain the pinions 28 in mesh with gears 29. Said springs also act, through the wire units 34, to hold the bar.32 away from the handle member 33, as shown in FIG. 3. If the fingers of the'hand grasping the handle and manipulating the device along the blackboard are then placed about the bar 32 and squeezed so as to draw the bar toward the handle, the wire units 34 will be placed under tension, and the drum 19 will be pulled away from the blackboard; the pinions 28 becoming dis engaged from the gears 29. The drum 19 will then cease to exert any erasing action on the blackboard 1 until the bar 32 is released, as will be evident. The adjustment screws 12 and 18 control the width of the device between the lip-engaging faces ofthe rollers 9 and 15 and the blackboard frame engaging faces of the friction rollers 30, and thus enable the latter to always have the necessary frictional driving engagement with the corresponding edge frames.

In order to catch practically all of the chalk dust as the blackboard 1 is erased, and to clean the erasing drum as the latter rotates and traverses the blackboard, the following structural features are provided:

Secured to and extending the full height of the device between the frame rails 6 on opposite sides of the drum 19 are catch receptacles 36. These receptacles thus extend the full height of the drum and face the same, having a width relative'to the diameter of the drum as great as is practicable. The vertical side edges of the receptacles are faced with beads 37 of foam rubber or similar yieldable material which engage the peripheral surface of the drum 19 from top to bottom thereof.

Drum-surface wiping and cleaning elements in the form of small-diameter helical springs 38 extend in vertically spaced relation between the beads 37 of each receptacle 36; said springs following the countour ofand closely engagingthe surface of the drum 19, and being then expanded or loaded somewhat so that they will have the most effective wiping and cleaning action.

In orderthat the drum 19 shall be thus wiped and cleaned over its entire area with the use of a comparativeIy small number of cleaning springs 33, such springs rextend diagonally or at an angle to a horizontal plane from end to end, as indicated in FIG. 3; one end of each spring being at a higher level than the opposite end of an adjacent spring.

A pull-out dust catching drawer 39 is slidably mounted in each receptacle 36. It may here be noted that while the receptacles 36 are fixed and immovable, and

the drum 19 may be drawn back from its normal position, the yielding nature of the beads 37 enables the :drum to be thus drawn back 'sufiiciently for the pinion .28 to clear the gear 29, Without any damage being done to the drum 19 or to the receptacles 36.

From the foregoing description it will be readily seen that there has been produced such a device as will sub- 4 stantially fulfill the objects of the invention, as set forth herein.

While this specification sets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention, as defined by the appended claims.

Having thus described the invention, the following is claimed as new and useful, and upon which Letters Patent are desired:

1. A blackboard erasing device comprising a frame, means mounting the frame for movement along the blackboard from one end to the other in either direction, a handle on the frame for manipulating the same, a vertical-axis rotary drum mounted on the frame and faced with yieldable chalk-erasing material normally engaged with the blackboard, and dust catching receptacles mounted on the frame on opposite sides of the drum opening from top to bottom to the drum with their vertical edges engaging the drum at circumferentially spaced points thereon.

2. A device, as in claim 1, with dust receiving drawers removably mounted in the receptacles at the bottom thereof.

3. A device, as in claim 1, with drum cleaning elements mounted on the receptacles and extending trans versely thereof between said side edges and engaging the portions of the drum exposed between said edges.

4. A device, as in claim 3, in which said elements are helical springs disposed in angular relation to the horizontal and so that one end of each spring is at a higher level than the opposite end of the spring next above.

5. An erasing device for a blackboard equipped with top and bottom edge strips, the device comprising a mounting frame, means supporting said frame from said strips for movement along the same in either direction, a handle on the frame for manipulating the same, a vertical-axis blackboard erasing drum mounted on the frame and normally engaging the blackboard, a verticalaxis friction roller mounted on the frame and engaging .one of said edge strips, and drive means for the drum including gearing connecting the roller and said drum.

6. A device, as in claim 5, in which said gearing com prises a pinion on the drum, and a relatively large gear on the roller.

7. An erasing device for a blackboard equipped with top and bottom edge strips, the device comprising a mounting frame which includes top and bottom rails relatively close to and laterally out from said strips, and a member laterally out from the rails connecting the same in rigid relation; a handle for manipulating the frame mounted on said member, means supporting the frame from said edge strips, a vertical-axis blackboard engaging drum extending between the rails and having axial shaft units projecting from both ends thereof, means journaling the shaft units in connection with the rails, vertical-axis friction rollers mounted on the rails and engaging the related edge strips in driving relation, gears fixed axially with the rollers, and pinions normally meshing with the gears fixed on the shaft units.

8. A device, as in claim 7, in which said journaling means includes bearing collars through which the shaft units turnably project, the collars being slidably mounted on the rails for movement radially of the friction rollers in a plane at right angles to the blackboard, springs connected to the collars and rails to pull said collars toward the blackboard, a trigger bar mounted in connection with the handle and disposed in said plane, and pull elements extending between and connecting the bar and collars.

9; An erasing device for a blackboard equipped with the same in rigid relation; a handle for manipulating the frame mounted on said member, a blackboard erasing member supported from and extending between the rails and normally engaging the blackboard, and means supporting the frame from the edge strips for movement along the same; such means comprising longitudinally spaced vertical-axis grooved rollers supported from each rail, a hanger mounted on the upper edge strip having a lip engaging in the grooves of the roller on the upper rail on the sides of said rollers opposite the blackboard, a strip mounted on the lower edge strip and having a lip engaging in the grooves of the rollers on the lower rail on the sides of said rollers opposite the blackboard, and a roller on each rail centrally between the first named rollers and engaging the related edge strip.

10. A device, as in claim 9, with means mounting the first named rollers on the respective rails for individual horizontal adjustment in a direction toward and away from the blackboard, and means to so adjust said mounting means.

11. An erasing device for a blackboard with a fixed strip along one horizontal edge, a rotary vertical axis blackboard erasing drum normally engaging the blackboard, axial shaft units rigid with and projecting from edge strip, a gear fixed with the roller, and a pinion fixed on the adjacent shaft unit and normally engaging the gear; the axis of the roller being disposed between the strip and said one shaft unit whereby when the bearings are moved away from the blackboard, the pinion will move out of mesh with the gear.

References Cited in the file of this patent UNITED STATES PATENTS 382,705 Kane May 15, 1888 1,232,815 Lapedes July 10, 1917 20 1,804,230 Raifs May 5, 1931 2,167,296 Farmer July 25, 1939 FOREIGN PATENTS 123,006 Sweden Oct. 13, 1948 

1. A BLACKBOARD ERASING DEVICE COMPRISING A FRAME, MEANS MOUNTING THE FRAME FOR MOVEMENT ALONG THE BLACKBOARD FROM ONE END TO THE OTHER IN EITHER DIRECTION, A HANDLE ON THE FRAME FOR MANIPULATING THE SAME A VERTICAL-AXIS ROTARY DRUM MOUNTED ON THE FRAME AND FACED WITH YIELDABLE CHALK-ERASING MATERIAL NORMALLY ENGAGED WITH THE BLACKBOARD, AND DUST CATCHING RECEPTACLES MOUNTED ON THE FRAME ON OPPOSITE SIDES OF THE DRUM OPENING FROM TOP TO BOTTOM TO THE DRUM WITH THEIR VERTICAL EDGES ENGAGING THE DRUM AT CIRCUMFERENTIALLY SPACED POINTS THEREON. 